The present invention relates to processes for the preparation of polyarylethers without the use of azeotropic cosolvents. The present invention also relates to the use of polyarylether containing reactor solutions in the preparation of membranes and the products thereof.
Commercially used polyarylethers, such as polysulfone, polyethersulfone, and polyphenylsulfone, have been prepared in dipolar aprotic solvents such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, and diphenylsulfone. However, the reaction byproduct, water, is a poison to these reactions. An azeotropic co-solvent has been used, such as toluene or chlorobenzene, to remove the water azeotropically during the polymerization. In general, these polyarylethers have to be isolated from the solvents, and are marketed either as pellets or powders. An end-user, such as a membrane manufacturer, redissolves these polymers in an appropriate solvent to make membranes out of solution of the redissolved polymers.
U.S. Pat. No. 4,105,636 relates to aromatic polyethers made by heating an organic sulphoxide or sulphone solvent containing i) a mixture of a bisphenol and an aromatic dihalo compound or ii) a halophenol, in which the halogen atoms in the dihalo compound or halophenol are activated by ortho or para —SO2— or —CO— groups, and an alkali metal carbonate. The water produced by the reaction is removed by distillation in the absence of an azeotrope forming solvent.
U.S. Pat. No. 5,047,496 relates to a process for the preparation of high molecular weight aromatic polyethersulphones from diphenols and dihalogenoaryls, characterized in that N-alkylated acid amides are used as solvents and at the same time for the azeotropic removal of the water from the reaction.
U.S. Pat. No. 6,437,080 B1 relates to a process for the preparation of a polymer composition having at least one aromatic or a mixture thereof with the process involving: i) obtaining a reaction mixture comprising polymer precursors in a first fluid boiling in excess of 100° C.; ii) subjecting the reaction mixture to a first elevated temperature in excess of 100° C. to generate the alkali metal salts of polymer precursors and the polymer reaction products thereof; and iii) subjecting the reaction product mixture to at least a second temperature and isolating the reaction product in the form of a polymer composition which is substantially insoluble in a second fluid, from the first fluid which is substantially soluble in the second fluid, by contacting with an amount of second fluid. U.S. Pat. No. 6,437,080 B1 also relates to a process indicated therein to be conducted in substantial absence of an effective amount of an azeotrope.
Japanese Patent Publication No. 2006-111665 A relates to a method for producing a polyarylene-based polymer by polycondensing an aromatic dihalide compound with a dihydric phenol compound or a dihydric thiophenol compound in the presence of an alkali metal compound in an organic polar solvent. The method is characterized by using a solvent which can be mixed with water, is liquid at ordinary temperature, and has a boiling point of ≧200° C., and then carrying out a polycondensation reaction at the boiling point of the organic polar solvent or at a temperature near to the boiling point in the flow of an inert gas, while removing the by-produced water on the outside of the reaction system together with the organic polar solvent.
Chinese Patent Publication No. 101580584 A relates to a block sulfonated aromatic poly (thio) ether preparation method with the use of sulfonated monomers, non-sulfonated monomer and bis(thio)phenol monomers as starting material in high-boiling aprotic solvent carbonate under alkaline conditions, with the reaction conducted for 10-24 hours, the temperature controlled at 150-200° C., for the preparation of block sulfonated poly aromatic (thio) ether polymers. Chinese Patent Publication No. 101580584 also relates to methods indicated therein to omit toluene as organic solvent and a step for azeotropic water separation.
The present inventors have recognized that it would be desirable to provide a process for making polyarylethers without azeotropic cosolvents in an economically attractive manner, wherein membrane filtration products having suitable physical and performance properties can be manufactured directly from the reactor solution.